bottom-sheet: tweak UI

- re-add thepand icon, shaped like a pill
- round top corners

react/features/toolbox/components/native/styles.js

@@ -55,6 +55,18 @@ const whiteToolbarButtonIcon = {
  */
 const styles = {
 
+    expandMenuContainer: {
+        alignItems: 'center',
+        borderTopLeftRadius: 16,
+        borderTopRightRadius: 16,
+        flexDirection: 'column'
+    },
+
+    sheetGestureRecognizer: {
+        alignItems: 'stretch',
+        flexDirection: 'column'
+    },
+
     /**
      * The style of the toolbar.
      */